CRC16

 Function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. - Calculates a CRC16 on the characters of a string.

Inputs

Input	Data Type	Range	Unit	Default	Description
IN	STRING				Character string.

Outputs

Output	Data Type	Range	Unit	Description
Q	INT			CRC16 calculated on all the characters of the string.

Remarks

• The function calculates a Modbus ModBus is a serial communications protocol and is now the most commonly available means of connecting industrial electronic devices. ModBus is often used to connect a supervisory computer with a remote terminal unit in supervisory control and data acquisition (SCADA) systems. Versions of the ModBus protocol exist for serial port and Ethernet (it is widely used with TCP/IP over Ethernet) CRC16, initialized at 16#FFFF value.

FBD Language Example

FFLD Language Example

• In the FFLD "Free Form Ladder Diagram" Language, the input rung (EN) enables the operation.
  • The output rung (ENO) keeps the same value as the input rung.
  • The function is executed only if EN is TRUE.

IL Language Example

• In the IL "Instruction List" This is a low-level language and resembles assembly Language, the input must be loaded in the current result before calling the function.

Op1: LD "Ladder diagram"
Ladder logic is a method of drawing electrical logic schematics. It is now a very popular graphical language for programming Programmable Logic Controllers (PLCs). It was originally invented to describe logic made from relays. The name is based on the observation that programs in this language resemble ladders, with two vertical "rails" and a series of horizontal "rungs" between them    IN
     CRC16
     ST    Q

ST Language Example

Q := CRC16 (IN);